Patients with a broken vertebra and/or degenerative disc disease often have a deformed spine caused by trauma or the like due to a collapsed vertebra. The deformed spine results in a scoliotic or kyphotic spine. The usual treatment for such a condition where the adjacent vertebrae are collapsed is a fusion of the vertebrae concerned. With fusion, after accompanying repositioning of the spine during surgery, the deformed spine is returned to its desired anatomical shape. However, after fusion the adjacent levels of the spine experience increased movement as the adjacent levels must compensate for the immobility of the fused vertebrae. This results in higher strains for the adjacent levels and discs, leading to more disc disease problems and back pain.
While various artificial vertebrae have been proposed in the prior art to serve as a replacement for a damaged vertebra, and thus to help avoid the problems associated with fusion, this requires removal of the damaged vertebra. An example of such a replacement vertebra is shown in US Published Application 2005/0060034 to Berry et al.
Another major improvement in the treatment of the spine are intervertebral implants of the type which provide articulation such as universal movement between upper and lower endplates thereof, and hence between adjacent vertebrae. Examples of such intervertebral implants are those disclosed in US Published Applications 2005/0085917 (Marnay et al.) and 2004/0117022 (Marnay et al.); and examples of exemplary tools and methods for insertion of such intervertebral implants are those disclosed in International Published Application No. WO01/19295 (Beyersdorf et al.) and in US Published Applications 2004/0215198 (Marnay et al.), 2005/0021042 (Marnay et al), and 2004/0117022 (Marnay et al.). The disclosures of these published applications are hereby incorporated by reference. However, such intervertebral implants are not currently adaptable for use with broken or damaged vertebrae.
Besides trauma or the like which results in a deformity, natural miss-shaping of vertebrae may also result in a deformity or undesired curvature of the spine. Typical of such conditions are scoliosis or kyphosis.